A362485 Number of numbers k such that iphi(k) = n, where iphi is the infinitary totient function A091732.

2, 2, 2, 2, 0, 4, 0, 4, 0, 2, 0, 6, 0, 0, 2, 4, 0, 4, 0, 2, 0, 2, 0, 10, 0, 0, 0, 2, 0, 6, 0, 4, 0, 0, 0, 8, 0, 0, 0, 4, 0, 2, 0, 2, 2, 2, 0, 14, 0, 0, 0, 2, 0, 2, 0, 2, 0, 2, 0, 10, 0, 0, 0, 4, 0, 4, 0, 0, 0, 2, 0, 14, 0, 0, 0, 0, 0, 2, 0, 8, 0, 2, 0, 4, 0, 0

Offset: 1

Author

Amiram Eldar, Apr 22 2023

Keywords

• nonn

Comments

a(n) is even for all n, because if k is a solution to iphi(k) = n, and A007814(k) is even, then 2*k is also a solution, i.e., iphi(2*k) = n.

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Row lengths of A362484.

Cf. A007814, A091732, A362486 (positions of 0's), A362487 (indices of records).

Similar sequences: A014197, A063740, A361967, A362181.

Programs

Mathematica

a[n_] := Length[invIPhi[n]]; Array[a, 100] (* using the function invIPhi from A362484 *)

Formula

a(A362486(n)) = 0.